Auxiliary drive belt contact & tension

[SwannyUK]

Further to my last post regarding my P/S pump swap, I'm still getting a little judder on steering, but nowhere near the level that I was before.

I've taken a close look at the auxiliary drive belts, and after tensioning the PS and water pump belt to 'around 10mm with a firm thumb press', i've taken a look at the contact patches on the belts. Do you think that the PS and WP belt isn't getting enough contact with the pulleys?

Red is contact, yellow is not contacting. The PS belt seems to be getting much less contact than the other belts.

PS belt;



Other belts;



These are the belt models. I was wondering if you'd advise any belts with slightly better fitting profiles?

[griston64]

The 6469 belt is too wide at 13mm. The 6375 is the correct 11.9 mm wide

I always get gen Volvo belts from FRF

[bob12]

Personally I don't have a problem with Gates belts having used them on the 745 for countless years. I say 'countless' the current belts 6375MC (yes, they also fit a 745!!) are in good condition and have been in for at least xxx years!

As griston64 says ^^^ the secret is knowing the correct width, namely 11.9mm. If you are running with the original Volvo adjusters the length is fine setting up at about midway. The Gates Catalogue is quite helpful see: https://www.gatesautocat.com/

Bob

[SwannyUK]

Originally Posted by griston64

The 6469 belt is too wide at 13mm. The 6375 is the correct 11.9 mm wide

Ah! Superb, that'll do it then. I'll get myself another one sorted. Thanks so much!

I did wonder why it was tricky to get into on the pulley even when the adjuster was slackened all the way. it appears a 6469 is 975mm long, and the 6375 is 1010mm long.

Originally Posted by bob12

If you are running with the original Volvo adjusters the length is fine setting up at about midway.

About midway along the thread on the tension adjuster?

[bob12]

Originally Posted by SwannyUK

Ah! Superb, that'll do it then. I'll get myself another one sorted. Thanks so much!

I did wonder why it was tricky to get into on the pulley even when the adjuster was slackened all the way. it appears a 6469 is 975mm long, and the 6375 is 1010mm long.

About midway along the thread on the tension adjuster?

Yes, about midway on the adjuster is where my belts end up correctly tensioned.

The original Volvo ones provide a very large amount of adjustment leeway. It doesn't matter where the adjusting screw ends up as long as the belts are correctly tensioned.

Bob

[360beast]

I found gates belts stretched quickly on my 940 and one even snapped in less than a year, swapped to gen Volvo belts and been absolutely fine.

Part numbers are

Alternator belt with a/c 973487
without a/c 973982
Power steering belt 981680

I've not got the part number for the A/C belt as mine is removed as it leaks.

[griston64]

Originally Posted by 360beast

I found gates belts stretched quickly on my 940 and one even snapped in less than a year, swapped to gen Volvo belts and been absolutely fine.

Part numbers are

Alternator belt with a/c 973487
without a/c 973982
Power steering belt 981680

I've not got the part number for the A/C belt as mine is removed as it leaks.

What Luke said

[Forrest]

The correct Volvo parts for a turbo car with a/c are:

Aircon Compressor 977731 12.5mm x 950mm
Alternator 973487 11.9mm x 1013mm
Power steering 981680 (formerly 973488) 11.9mm x 1000mm

It is possible at a pinch to interchange the alternator and power steering belts but you'll find the adjusters are then on the limit. You might have completely to remove the power steering tensioner bolt to get enough adjustment to get the correct, shorter belt over the power steering pulley.

In theory, non OEM v-belts with those dimensions should work just as well but as others have said results and longevity can be mixed. Also, it is not unusual for non-OEM suppliers' part finders to specify belts with incorrect dimensions.

My policy for a while now has been to renew the auxiliary belts with Volvo parts when I do the timing belt. I now tension them using the old trick of adjusting them so that you can twist the longest section by 90 degrees having previously faffed about with a krikit gauge, ruler and so on and still ended up with a squealing belt.

Don't leave any of the accessories secured by the long, thin tensioner bolt. It is only intended for adjusting the static tension not supporting the accessory in use. Once you have torqued the securing bolts slacken off the tensioner slightly to preserve its bolt.

[SwannyUK]

Originally Posted by Forrest

Don't leave any of the accessories secured by the long, thin tensioner bolt. It is only intended for adjusting the static tension not supporting the accessory in use. Once you have torqued the securing bolts slacken off the tensioner slightly to preserve its bolt.

Ah! I'll bear that in mind thanks!